System and method for selectively controlling a solar panel in segments

ABSTRACT

A control system is provided for a solar panel. The control system includes a plurality of control elements that are individually connected to a corresponding segment of the solar panel. The control system also includes control logic that is structured to individually signal each of the plurality of control elements in order to cause the signaled control element to either switch-off or alter performance output to maximize the over all output of a solar panel or solar power generating system utilizing such panels.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/444,883, filed Jul. 28, 2014, entitled “SYSTEM AND METHOD FORSELECTIVELY CONTROLLING A SOLAR PANEL IN SEGMENTS”, which is acontinuation of U.S. patent application Ser. No. 12/643,266, filed Dec.21, 2009, entitled “SYSTEM AND METHOD FOR SELECTIVELY CONTROLLING ASOLAR PANEL IN SEGMENTS”, issued as U.S. Pat. No. 8,791,598, whichclaims benefit of priority to Provisional U.S. Patent Application No.61/139,603, filed Dec. 21, 2008, entitled “AN INNOVATIVE SOLAR PANELWITH EMBEDDED HARDWARE AND SOFTWARE FOR ENERGY MAXIMIZATION, RELIABILITYIMPROVEMENT, HIGHER AVAILABILITY, DIAGNOSTICS, MONITORING, CONTROLLING,OPERATION AND MANAGEMENT, MAINTENANCE AND TWO WAY COMMUNICATIONCAPABILITY”; the aforementioned priority applications being herebyincorporated by reference in their entirety.

TECHNICAL FIELD

Embodiments described herein pertain generally to a system and methodfor selectively controlling a solar panel in segments.

BACKGROUND

Conventional solar panels typically interconnect solar cells in series,with panel-level control using flying diodes to “shut-off” the entirepanel or part of the panel when output is compromised.

Conventional solar panels typically interconnect solar cells in series,with panel-level control to “shut-off” the panel when output iscompromised. FIG. 7 illustrates a conventional control system for asolar panel, under the prior art. A solar panel 702 includes segments710 that are interconnected to a junction box 706. The junction box 706is connected to an inverter 715, which has a maximum power point tracker(MPPT) component 725 that monitors and controls the whole panel. Under aconvention system, the MPPT tracks the maximum power point for thecomplete panel. Under a conventional approach, the segments 710, 712,714 are individually controllable to switch off using a correspondingdiode 710, 712, 714. The diodes 710, 712, 715 shut off the correspondingsegment 710, 712, 714 if an output of the segment drops below a minimumthreshold. The MPPT tries to adjust voltage/current values from theoutput of the whole panel in order to maximize the output power of thewhole panel. Under the conventional approach, MPPT, however, is unableto control individual segments to achieve true maximization.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a controlled solar panel assembly, in accordance withone or more embodiments.

FIG. 2 illustrates a CSC that is provided on a segment line (to connectto a corresponding segment), under an embodiment.

FIG. 3 illustrates an arrangement for implementing control and switchelements on panel segments connected in parallel, according to anembodiment.

FIG. 4 is a simplified illustration of an arrangement for implementingcontrol and switch elements on panel segments connected in series, underan embodiment.

FIG. 5 illustrates a regulator for use with any of the embodimentsdescribed.

FIG. 6 illustrates a method for controlling a solar panel, according toone or more embodiments.

FIG. 7 illustrates a conventional control system for a solar panel,under the prior art.

DETAILED DESCRIPTION

Embodiments described herein provide for segmenting control of a solarpanel in order to maximize the power output from the solar panel. Asdescribed, a solar panel can be segmented and controlled on aper-segment basis in order to enhance performance of the entire solarpanel.

In an embodiment, a solar panel is structured to provide a plurality ofsegments that are electrically interconnected in parallel. A controlelement is provided for each individual segment. The control element isconfigured to control an output from that segment independent of anoutput from other segments that comprise the solar panel.

In some embodiments, the control element for each one of the pluralitysegments includes a control and switch component (“CSC”) that isstructured to (i) adjust an electrical output of that segmentindependent of an electrical output of other segments, (ii) cut-off thatsegment without affecting an output of other segments that comprise thesolar panel.

Still further, some embodiments include control logic that is coupled toeach of the plurality of segments. The control logic is capable ofindividually signaling the control associated with each one of thesegments in order to cut-off or alter performance of that segment.

In some embodiments, a control system is provided for a solar panel. Thecontrol system includes a plurality of control elements that areindividually connected to a corresponding segment of the solar panel.The control system also includes control logic that is structured toindividually signal each of the plurality of control elements in orderto cause the signaled control element to either switch-off or alterperformance output.

A control system described with embodiments herein may be used tocontrol a solar panel comprising segments that are electricallyconnected in series or in parallel.

Still further, in some embodiments, a solar panel is controlled byidentifying a plurality of segments that form the solar panel. Theplurality of segments may be electrically connected in series and/or inparallel. Each of the segments is provided a control element to controlan output of that segment. The individual control elements areselectively controlled in order to affect an output from a correspondingsegment of the panel.

As used herein, a “solar panel” is a packaged or interconnected assemblyof photovoltaic cells (“solar cells”). A “segment” of a solar panelincludes one or more cells, including one cell or multi-cell clusters. Asegment may also correspond to a region of a solar panel. According toat least some embodiments, a panel is a package of solar cells thatinclude electrical terminals for providing an output of collective solarcells that are provided with the package.

System Description

FIG. 1 illustrates a controlled solar panel assembly, in accordance withone or more embodiments. A solar panel assembly 102 includes segments110, 112, 114, which can be interconnected in series (as shown) and/orin parallel. Each segment includes one or more solar cells. Inoperation, the segments 110, 112, 114 form a panel, and the individualsegments supply power on power lines 111, 113, 115 to a regulator 134,which in turn outputs power terminal of the junction box which isgenerally connected to inverters 151 or energy storage elements such asone or more batteries. The inverters convert the output of the panel 102into AC form. Some embodiments described include an intelligent junctionbox 141, which includes control logic 130 and voltage/current regulators134. The combined output of the segments 110, 112, 114 is controlledindividually, and regulated on both the segments and at the regulator134 in order to maximize or optimize the power output of the panel orsystem connecting the panels.

According to some embodiments, the junction box 141 can be structured toreceive power from more than one panel, and furthermore to use itsresources, including control logic 130, to selectively control segmentsof multiple panels that feed into the junction box.

System 100 further includes a plurality of control and switch component(CSC) 120, 122, 124. Each CSC is formed by a combination of elements,and individually assigned to a corresponding one of the segments 110,112, 114. As described below, each CSC includes (i) a resource orcomponent 147 for switching a corresponding one of the segments off,without affecting operation of other segments that comprise the panel;and/or (ii) a voltage booster to boost voltage as needed to enable powerusage from the segment and/or (iii) a voltage buck converter to lowervoltage as needed to enable power usages from the segment (collectivelybooster and buck converter are identified as a common element 149,although some embodiments may utilize only one of the buck converter orbooster). Each resource 147 can be implemented as part of a maximumpower point tracker (MPPT) in combination with one of the segmentdetectors 140, 142, 144. As an addition or alternative, the detectors140, 142, 144 may include segment-specific sensors, such as those thatdetect luminosity (thereby detecting luminosity at a particular regionof the panel). The CSC 120, 122, 124 may switch or control output inresponse to the occurrence of predetermined conditions. Detection (ofthe predetermined conditions) may be made on individual segments, apartfrom other segments, or on a panel (or multi-segment) basis. Morespecifically, segment detectors 140, 142, 144 can be used to detectsegment-specific predetermined conditions. In particular, the segmentdetectors 140, 142, 144 may monitor electrical output on thecorresponding segment, and then boost or switch the segment out inresponse to the electrical output dropping to predetermined thresholds.In some implementations, at least portions of the CSC 120, 122, 124and/or detectors 140, 142, 144 are provided as integrated circuitry andelectronics with the panel 102.

The system 100 further comprises control logic 130 that is connected tothe individual CSC 120, 122, 124. The control logic 130 is configured totrigger (i) switching and/or (ii) boosting or bucking in individual CSC120, 122, 124. The control logic 130 is able to selectively triggerindividual CSC 120, 122, 124 to switch/boost/buck corresponding segmentoff (or on) in response to detecting panel-level designated conditions.In addition to segment detectors 140, 142, 144, the control logic 130uses a combination of resources to detect the predetermined conditions.

According to some embodiments, the predetermined conditions (whetherdetected centrally, from control logic 130, or from segment detectors142, 144, 146) are detected by panel-level detectors, such asvoltage/current sensors, external sensors 148 (e.g. environmentalsensors) or programmatic detectors that receive or interpret conditionsfrom network data (as described below). As an addition or alternative,the predetermined conditions are detected from segment-specificdetectors 140, 142, 144 as described above. The response to detectingthe predetermined conditions may be made from panel-level logic (e.g.control logic 130), or from individual control elements (e.g. CSC 120,122, 124). In each case, the response may control individual segments ofthe panel to maximize an output of the solar panel as a whole. In oneembodiment, the predetermined conditions are detected by monitoringvoltage and current output on output power lines 121 of individualsegments 111, 113, 115, or on the power lines 127 supplied fromindividual segments. Still further, the detection of the predeterminedconditions may be performed by control logic 130 interfacing withvoltage and/or current regulators 134, output lines 139 to the junctionbox 141 output. In such embodiments, the control logic 130 may identify,for example, a load input or requirement from the panel. For example,the control logic 130 may be coupled or connected to junction box 141output to determine the load input.

As mentioned, some embodiments provide for use of one or more externaldetectors 148, including a clock or environmental sensors, such as thoseused to detect ambient temperature, luminosity, or other environmentalconditions that affect some or all of the solar panel. Weather, forexample, may cause the control logic 130 to re-optimize desired powersettings. For example, in extreme hot or cold weather, the control logic130 may accept lower efficiency from the segments, and adjust outputthresholds accordingly.

As another addition or alternative, the control logic 130 is connectedto a network interface 160. The network interface enables networkcommunications to be sent to (or received from) the control logic 130.The network interface 160 enables, for example, control settings to becommunicated to the control logic 130 based on a centralized, remotecontroller that takes into account factors such as the weather at thelocation of the panel. Alternatively the network interface 160 receivesweather reports and interprets environmental conditions from them. Thus,the network interface 160 enables another resource from which controlresource 130 can detect or determine the existence of predeterminedconditions.

Still further, some embodiments provide for control logic 130 to sendout data, including malfunction errors or other communications that mayindicate the panel or some other component requires service. Forexample, if the panel is not performing well (e.g. section breaks aftera storm), a report is communicated out to a service or operator(including possibly the home owner) to indicate that the panel'sperformance is below an acceptable or expected level.

According to an embodiment, control logic 130 combines with the CSC 120,122, 124 to selectively switch and/or control output of individualsegments 110, 112, 114 in response to the detected conditions. Themultiple CSC are operated in order to (i) optimize output of the panelas a whole, given performance of individual segment; (ii) optimizeperformance of individual segments; (iii) optimize performance of awhole system that uses multiple panels. In particular, embodimentsrecognize that performance degradation in one or more segments 110, 112,114 can disproportionately affect performance of the panel as a whole orsystem as a whole. Accordingly, the control logic 130 selectivelyswitches segments 110, 112, 114 that are degrading the output orperformance of the entire panel, while maintaining those segments 110,112, 114 that maintain or enhance performance of the panel. Stillfurther, some embodiments recognize that even those segments that have adegraded output (due to, for example, shade) can be kept alive on thepanel, so long as others that are diminutive to performance areselectively switched off.

Control Elements

FIG. 2 illustrates a CSC that is provided on a segment line (to connectto a corresponding segment), under an embodiment. The CSC 200 is shownon segment line 201, connected to receive power from an assigned segment208. In some embodiments, the CSC 200 is provided as integrated orembedded circuitry and components of the panel. The CSC 200 includes (i)switch 210, and (ii) booster 220. In one embodiment, the switch 210 isfrequency controlled to maximize power on the segment line. Inmaximizing the power on the line, the switch 210 is operated at afrequency that sets the voltage and current to values that create themaximum power output. The segment detector 230 may make measurements onthe segment line 201 to determine power and current levels. Thedetermination of segment detector 230 may affect control components 240that set the frequency of the switch 210. In particular, control signal211 originates from the segment detector 230 (via control component240), or from the control logic 130 (see FIG. 1), in order to (i) adjustfrequency or (ii) cut-off the segment to avoid panel degradation. Thebooster 220 uses voltage and current readings from the segment detector230 to increase or decrease voltage under Ohm's law. In oneimplementation, the booster 220 operates to ensure that the voltageoutput 231 on the segment line 201 is of a optimum value, such as thatvalue required to be handled by a power inverter. In otherimplementations, the booster 220 operates intelligently, to optimizevoltage levels based on other conditions, such as output from otherlines or load conditions. A control signal may optionally be supplied tothe booster 220 (from control logic of the panel, or segment detector230) to enable intelligent performance.

FIG. 3 illustrates an arrangement for implementing CSC on panel segmentsconnected in parallel, according to an embodiment. With reference toFIG. 3, the CSC 310 of one segment 320 can boost or cut-off the outputon segment line 301. Embodiments recognize that the segments 310,structured in parallel on the panel 300, enable CSC 310 to simply switchthe affected segment off, without affecting the remainder of thesegments of the panel 300. Thus, a condition affecting one segment (e.g.partial shading) does not disproportionately degrade the output of theentire panel. According to some embodiments, each CSC 310 is responsiveto a condition on the line of the corresponding segment 320 (e.g. asdetermined from voltage or current). As an addition or alternative, eachCSC 310 may be individually signaled from control logic that responds toa condition that is determined from the panel as a whole. As describedwith an embodiment of FIG. 1, a junction box 350 may receive power fromthe segments 310, and include control logic, network interface, and/orregulators (as described with an embodiment of FIG. 1). The junction boxmay connect to the inverter(s) 340, so that the collective output of thesegments 320 are supplied to an inverter 340 via the junction box output(see FIG. 1).

FIG. 4 is a simplified illustration of an arrangement for implementingCSC on panel segments connected in series, under an embodiment. In manyconventional solar panels, solar cells are arranged in series inserpentine fashion. Similarly, embodiments recognize that for panel 400,CSC 410 may be implemented in series between segments (which can be morethan one solar cell). The segments 420 arranged in series have inputsand outputs that float, based on performance or output of the precedingelement. According to some embodiments, the CSC 410 is provided betweenat least some of the segments connected in series. The CSC 410 can bepositioned and structured to monitor the output of individual segments410 to determine acceptable power output, moderate power output, orunacceptable power output from any one segment. In some embodiments, theCSC 410 includes switch elements 420 that are structured to switch on abypass 412 for a given segment, in response to designated conditionsthat include determining that particular segment is not performing. Inthe example provided, a first segment 420 a has no detectable problemsas detected by CSC 410 a, and its output is supplied to a second segment420 b. The second CSCb 420 detects a predetermined condition that it maytreat, such as with boost (as described with prior embodiments) or powersetting (as described with prior embodiments). The second CSC 410 b mayalternatively (if the condition is sufficient) switch the second segment420 b off, and implement bypass 412 to cut-off the output of the secondsegment 420 b, while simultaneously directing the input of the secondsegment 420 b to the third segment 420 c. Thus, the determination forimplementing bypass 412 may be based on, for example, voltage or currentreadings from the particular segment (particularly as compared tovoltage or current readings of a prior segment), or sensor information(e.g. luminosity over particular segment is low). Each CSC 410 mayoperate and perform similar functions described with an embodiment ofFIG. 3, with the added function of switching into the bypass 412, ratherthan switching off. The bypass 412 removes the dependency of succeedingsegments on the affected segment.

With reference to FIG. 4, other embodiments provide that the individualCSC elements 410 a, 410 b, 410 c may buck or boost the output of onesegment into another. The CSC elements 410 a, 410 b, 410 c may trackdesired or expected output from each segment (which, when connected inseries, float). The CSC elements 410 a, 410 b, 410 c, either operatingindividually or with panel-level logic 430, may boost or buck outputfrom one segment into the other when predetermined conditions occur(e.g. output from one segment drops).

FIG. 5 illustrates a regulator for use with any of the embodimentsdescribed. A regulator 500 serves to intake power from segments of thesolar panel, and regulate output from the panel for voltage and current.The output of the regulator may be supplied to an inverter 570.According to some embodiments, regulator 500 includes one or moreindividual intake storage elements 510, 512, 514 for correspondingsegments. Each storage elements 510, 512, 514 outputs to a correspondingconstant voltage/current regulator 520, 522, 524. The constant output isprovided to a voltage/current mixer 525, which combines thevoltage/current from the different sources, and ensures the operationalcurrent and voltage requirements of the inverter 570 are met. Accordingto some embodiments, control logic 530 implements panel level control bycontrolling individual storage 510, 512, 514 from respective segments.Control logic 530 signals control signals 532 to storage elements 510,512, 514 to increase or decrease (i) amount charge stored in eachstorage element, and/or (ii) amount voltage/current signaled from thestorage elements 510, 512, 514. The control logic 530 is responsive tothe occurrence of predetermined conditions or input. In one embodiment,network interface 560 is used to receive data or control informationfrom a remote source, and control logic 530 is responsive to thatcontrol. Still further, detectors 540, which include, for example,environmental sensors, may provide information to the control logic toidentify the occurrence of the predetermined conditions. Detectors 540may also read current voltage values from, for example, the bus thatextends from some or all of the individual segments.

According to some embodiments, the control logic 530 may increase theoutput from one of the storage elements 510, 512, 514 when one of thesegments is providing lesser output than the other segments. In suchinstances, the predetermined condition corresponds to the output fromone of the segments, and the control signals 532 trigger increase powerout of storage elements 510, 514, 516 corresponding to other segments.

In other applications, the control logic 530 can detect a conditioncorresponding to when the panel, or individual segments, produces morepower than specified than operational parameters of the system (e.g. toomuch sunshine with luminating cloud cover). The control logic 530 mayreduce the power output from one or more of the storage elements 510,512, 514 in response to such conditions.

Still further, the network interface can receive control information,such as information indicating ‘down time’ for the load, and then usethe control logic to reduce the output from the storage elements 510,512, 514.

As an addition or alternative, the output from the regulator 500 maysupply power to a battery source (rather than the inverter 570). Whenthe battery is fully charged, the power output from the storage elements510, 512, 514 may be reduced.

Methodology

FIG. 6 illustrates a method for controlling a solar panel, according toone or more embodiments. In describing a method, reference is made toelements of FIG. 1 for purpose of illustrating elements suitable forperforming a step or sub-step being described.

According to an embodiment, a panel is segmented, either in series or inparallel, so that it is divided (step 610). Each segment 120 may beassociated with a control element (e.g. CSC 120, 122, 124) that isindividually controllable to effect an output from that segment.

One or more predetermined conditions are then detected (step 620).Predetermined conditions may be segment specific, so as to be detectedusing one of the segment specific detectors 140, 142, 144 (sub-step624). Such detectors may, for example, detect an output of that segment,and detect that segment has dropped off. A panel detector 148 may alsobe used, such as one that detects environmental conditions or operatesin connection with network interface 160 (sub-step 628).

In step 620, the segments, either individually or in groups, orcontrolled to compensate for the detected conditions. As described withother embodiments, the compensation may include (i) switching oneparticular segment off (in response to, for example, output readingsfrom that segment which indicate its performance is degrading thepanel); (ii) setting voltage and current to maximize power from thesegment; and/or (iii) increasing voltage (and dropping current). CSCelements 120, 122, 124 associated with each segment may be used toimplement the compensation.

According to one embodiment, predetermined conditions that affect theindividual segments are detected in stages. When a first thresholdcondition is detected (634), respective CSC 420, 422, 424 boost oroptimize the output of the segment compensate. If a second threshold isdetected, the CSC 420, 422, 424 of the respective segment shut thatsegment off (638). Each CSC may be self-controlled (e.g. include logicand detectors that operate independently on that segment) and/orcentrally controlled (via control logic 130). When segments areinterconnected in parallel, individual CSC elements can switch offselect segments without further consideration. When segments areinterconnected in series, switch off of individual segments may beperformed via a bypass.

Alternatives

While numerous embodiments described include segmenting a panel andassigning control elements to the individual segments, embodimentsrecognize that panels may be constructed to be compact and part of alarger array of panels. In such embodiments, the panel and segment maybe the same (i.e. one segment per panel), and the array of panels maycomprise segments of panels (“array segments”) that are interconnectedin series or in parallel. Control elements such as described may beimplemented to control individual array segments (i.e. one or morepanels). Specifically, embodiments provide for array segments,interconnected in parallel or in series, which can be assignedindividual control elements (e.g. control and switch elements) in orderto (i) set the voltage/current from the array segments to optimal ormaximum levels; (ii) boost the voltage from the array segments, and(iii) cut the array segments off from the array. In some embodiments,the array segments are interconnected in parallel, in which case onearray segment may be shut off without affecting other array segments. Abypass such as described with an embodiment of FIG. 4 may also beimplemented for array segments connected in series.

As an addition or alternative, the output from a controlled solar powersystem may be supplied to a battery, or bank of batteries (rather thanto an inverter). In such embodiments, the control elements and logic maytake into account predetermined conditions that are inherent in charginga battery or battery bank. For example, as described with an embodimentof FIG. 5, the output from the junction box or regulator may beintentionally dropped when the battery is deemed fully charged.

Although illustrative embodiments have been described in detail hereinwith reference to the accompanying drawings, variations to specificembodiments and details are encompassed herein. It is intended that thescope of the invention is defined by the following claims and theirequivalents. Furthermore, it is contemplated that a particular featuredescribed, either individually or as part of an embodiment, can becombined with other individually described features, or parts of otherembodiments. Thus, absence of describing combinations should notpreclude the inventor(s) from claiming rights to such combinations.

What is claimed is:
 1. A control system for a solar panel, the controlsystem comprising: a plurality of control elements that are individuallyconnected to a corresponding segment of the solar panel, each segmentcomprising only a portion of the solar panel; and a control logic thatis structured to individually signal each of the plurality of controlelements in order to cause the signaled control element to eitherswitch-off or alter performance output.